1. Technical Field
The present invention relates to a droplet discharging device such as an inkjet printer and a method of detecting a discharge abnormality thereof.
2. Related Art
An inkjet printer to be one of droplet discharging devices discharges ink drops (droplets) from a plurality of nozzles, thereby forming an image on a predetermined paper. An inkjet head (a printing head) of the inkjet printer is provided with a large number of nozzles, and there are some cases in which the ink drops cannot be discharged because some of the nozzles are clogged due to an increase in the viscosity of an ink, the entrainment of bubbles or the adherence of dust or paper dust. If the nozzles are clogged, dot dropouts are produced within an image so that image quality is deteriorated.
In order to eliminate such a drawback, as a device for checking whether ink droplets are discharged or not, there has conventionally been known a device for detecting a change in the intensity of a light which is caused by the passage of the ink droplets through a light emitting unit and a light receiving unit provided with nozzles for discharging an ink interposed therebetween, thereby confirming the operation of each of the nozzles by the light emitting unit and the light receiving unit (for example, see JP-A-2002-192740 Publication).
In a conventional device for optically detecting whether or not ink droplets are discharged from each of the nozzles, however, there are the following drawbacks.
More specifically, a space for installing an optical sensor is required, and furthermore, a detecting position in which the ink droplets pass through a light receiving region is set to be high or precision in a detection timing is to be enhanced in order to detect very small ink droplets with a high sensitivity.
In consideration of the respects described above, it is an object of the invention to provide a droplet discharging device which does not require a special sensor such as an optical sensor and can enhance the reliability of precision in the detection of the discharge abnormality of ink droplets by a comparatively simple structure, and a method of detecting a discharge abnormality thereof.